1. Field
The disclosed concept relates generally to current sensing and, more particularly, to circuits for sensing direct current (DC) flowing through a conductor.
2. Background Information
DC current sensing assemblies have been employed in electrical switching apparatus, such as circuit interrupters, to measure the current flowing therethrough. DC current sensing assemblies that use magnetic sensors require a corresponding circuit to amplify the output signals of the magnetic sensors. The corresponding circuit must also be able to handle both positive and negative currents through the circuit interrupter. Present designs use multiple methods for sensing positive and negative currents. Some will use one channel with a split voltage rail assigning a negative or positive sign based on voltage above or below the mid-point of the voltage range. Some will use two channels to achieve greater sensing range, higher resolution and accommodate auto ranging features.
DC current sensing assemblies should also preferably minimize errors from sensor and amplifier off-sets and temperature drift, as well as have the wide sensing range that is associated with the operating range of circuit breakers. The magnetic sensors themselves should also be low cost and very robust with a high durability.
There is room for improvement in current sensing assemblies.
There is also room for improvement in current sensing circuits.